Drill pipe protector



Nov. 1, 1955 N. K. TSCHIRLEY 2,722,462

DRILL PIPE PROTECTOR Filed March 20, 1952 Fig./.

22 Fl g 24 1 Norman K. Tschirley 1i INVENTOR.

United States Patent Office 2,722,462 Patented Nov. 1, 1955 DRILL PIPEPROTECTOR Norman K. Tschirley, McAllen, Tex. Application March 20, 1952,Serial No. 277,557 6 Claims. (Cl. 308-4) This invention relates to adrill pipe protector and particularly to an elastic collar fitted on adrill pipe to prevent Wear of the drill pipe coupling on the side of thehole or casing.

In the operation of rotary drilling rigs the rotary drill pipe extendsdownwardly through a casing and is generally provided with a pluralityof sections which are held together by means of a coupling which is ofconsiderably larger diameter than the normal diameter of the drill pipe.In operation of the pipe there is a tendency for the drill rod to whipin the casing or in the hole causing the couplings to wear against theside of the casing and also causing the drill bit to have a tendency todrill an erratic hole. It has heretofore been proposed to provideelastic collars on the drill pipes to eliminate contact be tween thecouplings of the drill pipe and the side of the casing or hole and alsoto maintain the drill bit in substantially straight alignment with thecasing. The heretofore used protectors have decreased the actualdimensions of the mud space between the drill pipe and the casing or theside of the hole and has resulted in serious circumstances. Theincreased pressure of the mud because of the restriction provided by theelastic collar frequently causes the mud to flow outwardly into theformation being drilled through so that not only it is mud lost togetherwith the indications that could be received therefrom at the top of theWell but the mud that is lost in the formation may clog up the porestherein and prevent an otherwise good sand from bringing in a producingwell. Also, the obstruction to the flow of the mud causes a backpressure at the mud outlet jets so that the jetting action of the mud inthe drill bit is materially weakened.

The present invention provides an elastic collar of such formation thatthe total area between the collar and the casing is at no point lessthan the total area between the coupling in the drill pipe and thecasing. This invention, therefore, produces a protective collar which innowise limits the flow of the drill mud or produces back pressure in thewell. The drill collar of the present invention, therefore, permits themud to flow upwardly along the drill pipe without any undue restrictionso that the mud does not flow into the formation or have high backpressure resulting in injury to the tools or the diminution of thedrilling action.

The protector according to the present invention is provided with anelastorner collar snugly mounted on the drill pipe preferably adjacentto the coupling and having a normal diameter considerably less than thenormal diameter of the coupling. A row of uniformly disposed projectionsor protrusions preferably of substantially hemispherical shape aremounted on the outer circumferential surface of the elastomer collar,the outermost point of these projections extending well beyond themaximum outside surface of the coupling. The relative proportions of thepipe casing, drill pipe coupling and clastomer collar, including theprojections thereon, are such that at any point along the collarincluding a projection, the total cross-sectional area available for thepassage of mud between the collar and the casing is substantially equalto the total cross-sectional area for the passage of said mud alongsidethe coupling.

It is accordingly an object of this invention to provide an elasticdrill pipe protector.

It is a further object of this invention to provide a drill pipeprotector which in nowise restricts the crosssectional area for mudflow.

A further object of this invention is to provide a drill pipe protectorhaving a row of projections spirally therearound.

Other objects and many of the attendant advantages of this inventionwill be apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

Figure 1 is a vertical elevation partially in section of a drill rod andprotective collar within a section of a well hole;

Figure 2 is a cross-section through the drill pipe coupling takensubstantially on line 22 of Figure 1 showing the projections extendingthereabove; and

Figure 3 is a cross-section taken substantially on the plane indicatedby the line 3-3 of Figure l and indicating the difference in outsidediameters between the elastic collar and the pipe coupling.

in the exemplary embodiment according to the invention a well pipe hole10 is outlined by a casing 12 through which extends a rotary drill pipehaving sections 14 and 16 connected together by the usual coupling 18.The coupling 18 defines a space 20 between the casing and the couplingthrough which the drill mud must return to the top of the well. It willthus be seen that the space 20 determines the freedom of flow of thedrilling mud and particularly the pressure at the bottom of the Well sothat unless the space is of sufiicient size there will be danger of highpressure at the bottom of the well. To prevent the coupling 18 fromcoming in contact with the casing 12, a collar 22 of elastomer materialis placed on the drill pipe 14 adjacent to the coupling 18. The collar22 is preferably a snug or tight fit on the drill pipe 14 so that thereis little tendency of thecollar to slide or slip along the drill pipe.The normal outside diameter of the elastometer collar 22 is materiallyless than the normal outside diameter of the coupling 18 so that the.

space 24 between the collar and the casing is of greater width than thespace 20 between the coupling and the casing 12. The protecting elementsaccording to this invention now include a row of projections 26 arrangedin spiral formation about the surface of the elastomer collar 22 andpreferably of such dimensions that they extend materially above theoutside diameter of the coupling 18 as is best seen in Figures 2 and 3.The projections 26 may be of any desired shape but are preferablysubstantially hemispherical and are so arranged that the transversecross-sectional area of a projection 26 is equal to the difference incross-sectional area between the outside diameter of the collar 22 andthe outside diameter of the coupling 18. In other words, the totalcross-sectional area through the drill pipe and collar 22, including aprojection 26, is substantially equal to the total cross sectional areathrough the drill pipe and coupling 18. It will thus be seen that at anypoint along the collar 22, including a projection 26, the totalcross-sectional area available for the passage of mud is substantiallyequal to the total cross-sectional area for passage of such mud betweenthe coupling 18 and the casing 12.

It will thus be seen that the collar 22 plus its protecting projections26 in nowise inhibit the flow or" the drilling mud over the normalinhibitions produced by the necessary couplings in the drill pipe. Theprotective collar can thus be applied to the drill pipe to maintain thepipe in substantial alignment in the central portion of the easingwithout causing excessive loss of mud into the formation through whichthe pipe passes or the reduction of drilling efficiency because of thehigh pressure of mud at the drill head.

-'While a preferred embodiment of the invention has been shown anddescribed according to the present understanding thereof, it will beapparent to those skilled in the art that many changes and modificationscan be made therein without departing from the true spirit of theinvention.

Having described the invention, what is claimed as new is:

1. A string of drill pipe having lengths of pipe connected by enlargedcouplings and operable in a well casing, a drill pipe and easingprotector comprising a cylinder of elastomeric material tightly engagingthe drill pipe, projections on the outer surface of the cylinder, saidprojections being uniformly distributed over the length andcircumference of the cylinder simultaneously, the perpendicular distancefrom the axis of the drill pipe on which the cylinder is mounted to theextremity of any of the projections being greater than the perpendiculardistance from the axis of the pipe to the outer surface of the coupling,the perpendicular distance from the axis of the pipe to the surface ofthe cylinder being less than the perpendicular distance from the axis ofthe pipe to the outer surface of the coupling, the total enclosed areasurrounding the pipe and the protector including a pro jection, beingsubstantially equal to the total enclosed area surrounding the pipe andcoupling.

2. In combination, a well casing, a drill pipe having enlarged couplingsand operating in said casing, a drill pipe and easing protectorcomprising a cylinder of elastomeric material sprung over the couplingand tightly gripping the drill pipe, the perpendicular distance from theaxis of the pipe to the outer surface of the cylinder being less thanthe perpendicular distance from the axis of the pipe to the outersurface of the coupling; projec-tions on the outer surface of thecylinder, said projections being distributed uniformly over the lengthand circumference of said cylinder simultaneously whereby the enclosedarea at any point over the length of the protector will be nearly equalto the enclosed area over the length of the coupling; the outermostpoint of said projections extending beyond the outer diameter of thecoupling while providing at least as much clearance between the outsideof the drill pipe and the inside of the casing as is provided betweenthe pipe coupling and the casing.

3. In a string of drill pipe constituted of lengths of pipe withenlarged couplings and operating in a well casing, a drill pipe andeasing protector combination comprising a cylinder of elastomericmaterial constructed to be sprung over the enlarged couplings of a drillpipe and to grip the drill pipe tightly, projections on the outersurface of the cylinder and distributed over the length andcircumference of the cylinder simultaneously, the perpendicular distancefrom the axis of the pipe to the extremity of any of the projections onthe cylinder being greater than the perpendicular distance from the axisof the pipe to the outer surface of the pipe coupling in the string ofdrill pipe, the circumscribed area over the length of the protectorbeing from slightly less than to slightly greater than the circumscribedarea over the length of the pipe coupling, the protector being a part ofthe string of drill pipe and rotatable inside the casing with at leastas much clearance as is provided over the pipe coupling.

4. In combination a drill pipe having enlarged pipe couplings and acasing protector comprising, a cylinder of elastomeric material adaptedto be sprung over the pipe couplings in a string of drill pipe and togrip the pipe tightly, the perpendicular distance from the axis of thedrill pipe to the surface of the cylinder being permitted to equal butnot exceed the perpendicular distance from the axis of the pipe to theouter surface of the pipe couplings, projections molded on the outersurface of the cylinder and being distributed over the length andcircumference of said cylinder simultaneously so that the enclosed areaat any point over the length of the protector will be nearly equal tothe enclosed area over the length of the pipe couplings, and the tops ofsaid projections to extend beyond the outer diameter of the pipecouplings while still allowing at least as much clearance between theoutside of the drill string and the inside of a casing as is providedbetween the pipe coupling and the casing.

5. In combination, a cylindrical well casing, a rotary drill pipeoperating inside said casing, an elastomeric cylinder mounted on thedrill pipe and fitting inside the casing leaving at least as muchclearance for circulation of drilling fluid as is left by the pipecouplings in the string of drill pipe, projections disposed upon thesurface of the cylinder over its length so that as fluid is circulatedthrough the casing one of the projections at a time will add to therestriction of fluid flow beyond the restriction offered by theelastomer cylinder, and disposed upon the surface of the cylinder overits circumference simultaneously so that the pipe couplings and easingwill not contact each other when the drill pipe is rotated, raised orlowered inside said casing.

6. A device of the type described in claim 5, working as an integralpart of a string of drill pipe and allowing at least as much clearancefor the circulation of drilling fluid as is left by the couplings in thestring of drill pipe regardless of the combination of drill pipe andcasing sizes that might be used in cooperation to drill a given well.

References Cited in the file of this patent UNITED STATES PATENTS1,894,519 McLaine Jan. 17, 1933 1,959,367 Kennedye May 22, 19342,049,265 Kinney July 28, 1936 2,166,116 Bettis July 18, 1939 2,252,978Parkin Aug. 19, 1941 2,288,124 Creighton June 30, 1942

